Prevention of cyan dye fading in color developed prints and films



United States Patent PREVENTION OF CYAN DYE FADING IN COLOR DEVELOPED PRINTS AND FILMS James E. Bates, Carl E. Johnson, and Donald E. Tritten, Binghamton,'N.Y., assignors to General Aniline 8: Film Corporation, New York, N.Y., a corporation of Delaware No Drawing, Application January- 10, 1957 1 Serial No. 633,398

4 Claims, (CI. 96-56) The present invention relates to color photography andparticularly to a method and means for inhibiting the fading of cyan dyes in color photographic materials in which color images have been formed by color develop ment with a primary amino developing agent.

It is known that in certain processes of color forming photographic development color images are formed upon development byv the action of the oxidation product of a primary aromatic amino developing agent upon non-dif-- fusing color forming compounds or couplers located in the, emulsion layers. It is likewise known that the resulting. color images are susceptible to discoloration and fading when exposed to adverse conditions such as heat, high humidity, sunlight, or ultraviolet light. A commonly encountered type of color degradation is the loss of cyan density that occurs in color transparencies and prints which manifests itself by an overall reddish'tint in said transparencies and prints. This condition has been attributable to. the effect of moisture on the cyan dye images since the above condition can be accelerated by storing the color films or prints in a high humidity oven. The effect of light apparently plays little or no role in this type of cyan color degradation as the same effect is noticed in the' absence of light.

Although the aforesaid degradation or fading of the cyan layer may be associated with the adverse effects of high humidity, nevertheless some prints and transparencies, color developed as above, have greater resistance to cyan dye fading than others. Subsequent investigations which we initiated, revealed that greater stability to cyan fading was exhibited by the aforesaid color prints and transparencies which had been processed in localities wherein the water supply was. characterized by a hardness factor of over 300.p.p.m. On the other hand, when such color prints and transparencies were processed in areas wherein the water was relatively soft, the aforesaid cyan fading was very severe. It was therefore assumed that a correlation existed between the cyan dye fading and the degree of hardness of the water used for processing. Since water hardness is due to the presence of dissolved salts of magnesium and calcium, it was concluded that these salts contribute to the stabilizing effect of cyan dye fading.

Proceeding from this premise, we tested the effect produced by using a wash water containing water soluble salts of metals similar or analogous to magnesium and calcium, i.e., cadimum. It was found rather surprisingly that these salts, like those of calcium and magnesium, also operated to stabilize the cyan dye image.

It is therefore an object of the present invention to provide a method for preventing the fading and degradation of cyan dyes in colored photographic prints and transparencies, wherein the dyes are formed from oxidized color developer and a phenolic color former containing a long aliphatic chain.

A further object is to provide a composition which will function to prevent cyan dye fading in such color developed prints and transparencies.

Other objects will appear as the description proceeds.

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2 These objects are accomplished by either treating orbathing the finalcolor developed prints or transparencies in-a bath containing water soluble salts of calcium, magnesium, or cadmium, i.e., their chlorides, acetates, nitrates, bromides, and the like.

Thus, after the complete, processing of multicolor ma! terials containing color formers rendered fast to diffusion by virtue of a longaliphatic. chain, including color development, bleaching, fixing, and washing, and thena final treatment in a bath containing one of the above salts, it was found that the resulting color photograph showed a high resistance, to cyan, dyev fading or discoloration. This protection is, achieved without affecting, in anyway, the original color balance.

The concentration of the water soluble salts employed ranges from 1 to 5 grams per liter when added to the wash water, or from 1, to SO-grams per liter when used in a. final rinse bath. 1

The exact mechanism by which the aforesaid'salts cause inhibition of cyan dye fading is still unknown. It is our belief that the ions of the metals form highly insoluble metal salts or complexes with the cyan dye and thus give a product with much more resistance tothe effects of humidity. However, such an explanation is only theoretical and we do not wish to be bound or held in any man ner thereby.

The following table shows the stabilizing effect on cyan dye images produced as subsequently noted, of treating color prints or transparencies with a final bath contain-J ing, i.e., cadmium bromide.

Percent gain or loss in red absorption:

Deionized water wash :22 Deionized water wash followed by a final rinse bath CdB1' -13 The cyan dye stabilizing bath of the present invention can be used to, process a variety of photographic multicolor materials in which the dyestuff images are proces-= sed with non-diifusing color formers present in the emulsion. Said photographic multicolor materials include, color reversible film, color negative film, color reversible white printing material coated on an opaque base, and color positive printing'material coated on paper. The multilayer color reversible film containing color formers may be prepared by the methods described in U.S.'Patents 2,179,228; 2,179,239; 2,186,849; and 2,220,187, and con sists of an integral tripack emulsion coated on the usual clear film .base. Each of the emulsions is sensitized to one of the primary colors, namely, blue, green, and red. Usually the top layer is blue sensitive. The filter layer, yellow in color and blue absorbing, lies beneath the top layer. Below the said filter layer lies a green sensitive emulsion layer, and below this is a red sensitive emulsion layer. Each of the three emulsion layers contains a dye forming compound fast to diffusion which, during the development of a silver image by an aromatic amino developing agent forms, with the oxidation product of said developing agent, a cyan quinoneimine from a phenol coupler in the red sensitive layer, a yellow azomethine from an open chain ketomethylene coupler in the blue sensitive layer and a magenta azomethine from a pyrazoline coupler in the green sensitive layer. Generally the developed dye image is complementary in color to the color for which the emulsion layer is sensitized. A combination of these three printing primaries results in production of all the various hues and shades in the finished film or print.

After color development, it is necessary to remove the silver which is also formed duiing development. This is accomplished by use of a bleach such as acidified alkali permanganate or alkali dichromate solutions which convert the metallic silver into a water soluble silver salt or by other bleach solutions which transform the metallic silver into a silver salt which is soluble in fixer solutions, particularly sodium thiosulfate solutions. Certain bleach solutions of the second type include those which contain a halide and an oxidizing agent such as an'alkali ferricyanide, a cupric salt, or an alkali dichromate.-

The colored negative film is identical to the color reversible film with the exception that the former may contain an anti-abrasion layer or clear gelatin over the blue sensitive upper layer. The color reversible white opaque material is made in the same manner as the color reversible film and the color negative film with the exception that an opaque white pigment is incorporated into the film base. The positive color paper is also identical tothe color reversible film and the color negative film with the exception that a baryta coated paper base is used to hold theemulsion. The above-described negative, positive, and reversible materials also differ as to the relative speed and contrast of the individual emulsion layers and of the multilayer color materials. Preparation of photographic multilayer materials containing specific color formers fast to difiusion has been ture pertaining to color photography and is therefore not herein described.

The following examples describe in detail the methods forv carrying out the above objects of this invention but is to be understood that they are inserted merely for the purpose of illustration and are not to be construed as limiting the scope of the invention.

Example I The final treating bath is prepared as follows:

Cadmium bromide gm. 1.0 Reaction product of a phenol with ethylene oxide as per U.S.P.

2,213,477 gm. 0.5 Formalin ml. 15.0 Deionized water liters 1.0

Color prints or transparencies are treated for minutes in the above bath and are placed in high humidity ovens. One set was stored for hours at 90 C. and 70% R.H., and 85% R.H. A marked described in the litera- The above treating bath was used in the same manner as given in Example I.

Example III Magnesium sulfate (71-1 0) gm.-- 50.0 Formalin ml. 15.0

reaction product of Example I Deionized water liters 1.0

The same procedure was employed as given in Ex ample 1.

Example IV Cadmium bromide gm. 2.0 Deionized water liters 1.0

The pH of this solution was adjusted to 6.5 by the use of a small amount of a sodium acetate-acetic acid butler solution.

The treatment and testing were carried out as described in Example I.

We claim:

I. In the process of producing stabilized cyan color photographic images in a photographic material comprising a support and at least one light sensitive silver-halide emulsion containing a phenolic color former fast to difwater soluble salt of a metal selected from the class consisting of calcium, magnesium, and cadmium.

2. A process according to claim 1 wherein the said metal salt is a water soluble salt of calcium.

3. A process according to claim 1 wherein the said metal salt is a water soluble salt of magnesium.

4. A process according to claim 1 wherein the said metal salt is a water soluble salt of cadmium.

References Cited in the file of this patent UNITED STATES PATENTS ranges Handbook of Chemistry, 8th edition 1952 pages 784-789, Handbooks Publishers Inc., Sandusky, Ohio. 

1. IN THE PROCESS OF PRODUCING STABILIZED CYAN COLOR PHOTOGRAPHIC IMAGES IN A PHOTOGRAPHIC MATERIAL COMPRISING A SUPPORT AND AT LEAST ONE LIGHT SENSITIVE SILVER-HALIDE EMULSION CONTAINING A PHENOLIC COLOR FORMER FAST TO DIFFUSION CAPABLE OF FORMING, UPON DEVELOPMENT WITH A PRISMARY AMINO DEVELOPER, A CYAN QUINONEIMINE DYE IMAGE BY EXPOSING SAID MULTILAYER MATERIAL, COLOR DEVELOPING BLEACHING, FIXING, AND WASHING THE SAME, THE IMPROVEMENT WHICH CONSISTS OF AVOIDING CYAN DYE FADING BY TREATING THE SAID MATERIAL AFTER THE FINAL WASHING OPERATION WITH A WATER SOLUTION CONTAINING 1 TO 50 GRAMS PER LITER OF A WATER SOLUBLE SALT OF A METAL SELECTED FROM THE CLASS COMSISTING OF CALCIUM, MAGNESIUM, AND CADMIUM. 